Electrical indicating instrument



Feb. 4, 1930. M. E. CHENEY ELECTRICAL INDICATING INSTRUMENT Filed March10. 1926 Fig. 2

INVENTOR.

BY z Q ATTORNEYS.

Patented Feb. 4, 1930 UNITED STATES PATENT OFFICE MOSES E. CHENEY, OF LACBOSSE, WISCONSIN, ASSIGNOR, BY MESNE ABSIGNIEN'I'S, TO MOTO METER GAUGEa EQUIPMENT CORPORATION, 0]? LONG ISLAND CIT'Y, NEW

YORK, A CORPORATION 01' DELAWARE ELECTRICAL INDICATING INSTRUMENTApplication filed March 10, 1926. serial No. 98,806.

the market. This particular gauge comprises 10 in eneral a rheostat incircuit with current coi s and a source of current, having an armaturein the field of said coils and an indicating device connected with saidarmature. Both the rheostat and the indicating instrument are designedfor ready and easy assembly, and inthe one case the rheostat arm and inthe other the indicating pointer and armature are so arranged as to havethe proper movement, due to a new and improved asso- 2o ciation withother parts of the instrument.

It has been common practise to employ the differential type ofgalvanometer in electrical gasoline gauges for motor car use wherein twosolenoids or coils are used to take care in assembling proper y thearmature and coils to produce uniform increment of pointer movement andfurthermore it has been necessary to form the rheostat with a highresistance at one end and a low resistance at the other, in order toobtain this uniform increment of movement, and it has been necessarywith a support having high and low resistances at its opposite ends togive to the rheostat arm an eccentric movement, whereas with thisimproved apparatus the rheostat arm has a movement concentric with therheostat-support, while the uniform increment of pointer movement ismaintained throughout its travel. That with this type of electricalinstrument the rheostat support must have low resistance at one end anda high resistance at the other to produce uniform increments of pointermovement is best explained by assuming that the constant resistance ofthe coil in series with the rheostat is 35 ohms. Now, if the rheostatarm or wiper is at the point where the least rheostat resistance is inthe circuit, which we assume is nothing, the

of material variations of the voltage of the, current, but diflicult hasbeen experienced maximum current will pass through; that coil, which weshall assume to be the full position of the tank. Now, at the half fullposition the current through that coil must be ieduced "which means thattwice the resistance must beapplied to that circuit. In other words 35ohms must be'added to the coil resistance. Consequently, the rheostatresistance extending from one end of the support to its half way artmust be 35 ohms,

ut to indicate a A in condition the current must be reduced to 4 of itsoriginal amount or in other words t ere must be 4 times the originalresistance of 35 ohms which totals 140' 0 so that from the midway partto the point 70 ohms must be added as compared with only 35 ohms; fromthe mid-point to the opposite end of the rheostat support. Accordingly,in the same s ace represented b the armature movement rom the ,4position to the position an increasingly great resistance amounting to140 ohms must be added and in the s ace between the and positions 280 0ms resistance must be added if uniform increments of armature andpointer are to be maintained. All this goes to show that the rheostatsupport must be designed to take care of this unusual condition, if theuniform increment of pointer movement is to be preserved.

Referring to the drawings, Fig. 1 is a diagrammatic view showin theordinary type of rheostat in circuit with the battery and voltmeter.Fig. 2 is a detailed view of the spool or support for the rheostat wire.Fig. 3 is a plan view of the voltmeter. Fig. 4 is a transverse sectionalview on the line 1-1 of Fig. 3. Fig. 5 isa detailed view of the bracketfor supporting coils employed in the voltmeter.

Like parts are indicated by like figures of reference throughout thedifferent views.

Referring to Fig. 1 of the drawings, 1 indicates the rhesostat which isof the ordinary type illustrated in said Letters Patent to Winterhofi'excepting that the rheostat wire arm 3 of this rheostat is connected toa floatv or any other suitable device preferably in the manner fullyshown and described in said Winterhofl patent. As heretofore exlained,if this arm 3 is to travel with uniorm increments-of movement from thefull tank condition to the and positions the windings of the rheostatwire upon the spool or support must be such as to present lowresistances at one end and high resistances at the opposite end and theshape of this spool'is designed with that end in view. 2 indicates asource of electrical supply, preferably a battery. 4 indicates thevoltmeter referably shown as a ma etically otperated instrumentcontaining -t e novel eatures hereinafter more full described. In thisinstrument there are 5 own two coils of wire nested together in themanner indicated in Figs. 8 and 4, one coil being placed at an angle tothe other coil, and, as indicated in Fig. 4 the air gap in one coil ismuch wider than the air gap IILthB other. The coil supporting bracket(Fi 5) is of peculiar formation and is especia ly designed to supportthe two coils and to enable one of the coils to be readily adjusted intothe proper angular relation to the other coil for purposes ofcalibration. The main arm 6 of the bracket is shown as having flanges 7projecting upwardly therefrom andthese flanges are so arranged as to suport the main coil 8 on said bracket. A supp emental arm 9 projects fromthe main bracket arm and it is formed with flanges 10 and so arrangedthat the supplemental coil 11 will be supported on said supplemental armand the material of said supplemental bracket is of such character andso proportioned that the relative position of said supplemental coil canbe'readily changed whereby the instrument can be readily calibrated. Oneof the advantages in the apparatus described in the claims is that the1nstrument is readily calibrated, and another advantage is that theinstrument is ada ted to tanks of various sha es and styles 0installation, in some of w ich the float arm is. mounted eccentricallywithin the tank and by adjustin the head of the device the instrumentwill fit a great number of tanks. In calibrating this instrument, thepointer may first be set at Empty, then checked at the half-way point,i. e., the half-full point, and the proper calibration made by merelyadj usting the position of the end of the supplemental coil, movin ittowards or away from the end of the main coil then the travel of theointer may be checked and the length of tlie travel is corrected bychanging the osition of the su plemental coil so as to increase ordiminish the area of. the field and the effective magnetic strength ofthat field. In this way the apparatus described is susceptible to a verysimple and efficient method of calibration. As indicated in Fig. 3 thearmature 12' for the voltmeter is mounted at the point 12 and it is soarranged that the armature will move in an arc normall outside of thecoil windings but is capable of assuming a position such that portionsthereof will extend into the air gap of the coil and thereb cut into thecoil windings.

In addition to the fact that the location of the axis 12 for thearmature lends itself very well to the arrangement of parts, thislocation outside the longitudinal plane of the coils, is very advantaeous in assembling the parts and avoids the disadvantage of putting anyapertures throu h the coils.

The main coil, w ich may be termed the magnetic coil, is capable ofbeing connected directly across the electrical circuit of any make ofautomobile.- The other or supple mental coil, to ether with the rheostatin series, is also irectly connected across the electrical circuit, andis capable of being applied to any make of automobile. As indicated inFigs-1 and 3, the terminal a common to both coils is connected with thehigh or ungrounded side of the battery 2. The other end of the main coilis connected to the other side of the battery through the groundconnection 13 (Fig. 3) while the other end of the supplemental coil isattached to post 6 (Figs. 1 and 3) and through rheostat 1 to rheostatarm 3 to ground, thence to grounded side of battery 2.

It will be apparent that if the armature of the voltmeter revolves in anare outside of the windin s of the coils or cuts into the said windingst at it will in effect move in a cross field of magnetic lines of force,some of the lines of force being due to the .main or magnetic coil andthe other lines of force due to the supplemental coil and will take upositions corres onding with the direction 0? the resultant 0 these twomagnetic fields. By having the air gaps of the two coils proportionedsomewhat as indicated in the drawings and by having the coils placed inan ular relation somewhat as indicated in the rawings, it is possible toprovide for the proper calibration of the instrument and as thedirection of the resultant magnetic field is determined by the relativestrengths of the two individual fields, it will necessarily follow thatthe same variation in direction, time and degree in each of the twoindividual fields will cause no variation whatever in the direction ofthe resultant magnetic field. Consequently, it is evident that aninstrument constructed as indicated will not be aflected by variationsin the voltage of the electrical system of the automobile due to a lowbatterX or to the effect of the charging generator.

s indicated in Fig. 2 the wiring for the rheostat is wound about a spoolor supporting member marked 14 which is of peculiar formation, the maincharacteristic being that there is considerable variation in the widthof the spool, the object being to enable the ISO ' and 3 will indicatethat what has been designated the supplemental coil 11, is in serieswith the rheostat, and the battery 2, whereby the amount of currentpassing through said coil and hence the amount of flux surrounding it,will vary in accordance with the amount of resistance cut into thecircuit by means of the contact arm 3. On the other hand, coil 8 isconnected directly with the battery 2 and its flux is in no wiseeffected by the operation of the contact arm 3. Movement of said arm 3,however, will cause the armature 12 to move, due to the change in fluxwhich it produces in the coil 11 and hence gives an indication of thedepth of gasoline, for example, in the tank. It will also be evidentthat not only will change in resistance in rheostat 1 produce movementof the pointer, but were it not for coil 8, change in battery voltagewould also change in the pointer reading and hence introduce an errortherein. By the action of coil 8, however, any change in flux of coil'lldue to change in battery voltage is compensated for by a correspondingchange in the flux and coil 8, and hence chan e in battery voltage iswithout substantial eect upon the pointer.

Subject matter shown and not claimed herein is claimed in the divisionaland copending applications Serial No. 290,173

3. In an instrument of the character described, the combination of twocoils, bracket means for supporting said coils angularly positioned withrespect to each other, an armature pivoted in the enclosed angle andexternally of each of the individual coils, said bracket being of aconstruction to permit bending thereof to vary the angular relation ofsaid coils and the relation of at least one of said coils with respectto the armature.

In testimony whereof, I have hereunto set my hand this 23d da ofFebruary, 1926.

M SES E. CHENEY.

which relates to the combination of coils and rheostat; Serial No.295,952 which relates to the rheostat itself and Serial No. 257,816which relates to the relative positioning of the coils and the relativepositioning of coils and armature.

Having described the invention, I claim as follows:

1. In an instrument of the character described the combination of twosolenoids, one partially nested within the other, with an armaturerotatably mounted at a fixed point outside both solenoids in anunenclosed field adjacent said solenoids, one of said solenoids beingadjustably mounted, whereby its relation to its companion solenoid andto said armature may be changed.

2. In a diflerential galvanometer the combination of two coils, bracketmeans for supporting said coils with the coils arranged at an angle toeach other, and an armature pivoted adjacent said coils, said bracketmeans being of such construction as to permit bending thereof foradjusting the relative position of one of said coils.

